Retinal degenerative diseases and other forms of retinal damage are important causes of blindness. There is no effective treatment currently available. In the recent past, as experimental intraocular transplantation of retinal cells has been accomplished, investigators have wondered whether transplantation of retinal tissue into eyes blinded by retinal degeneration might offer an approach to restoration of sight. In animal studies, intraocular transplants of retinal tissue have revealed that immune responses must be taken into account. Since acceptance or rejection of retinal transplants is dictated, at least in part, by immune responses to the graft, this study is designed to evaluate the contribution of immunity to retinal transplant survival in the eye. Although a great deal has been learned about privilege in the anterior chamber of the eye, very little has been published on the putative immune privilege of the vitreous cavity or subretinal space. Since the eventual aim of our experimental approach is to transplant viable retinal tissues into the posterior region of the globe, our studies are also designed to evaluate immune privilege in these other ocular sites. Therefore, we plan experiments to answer the following questions: 1.Can different types of retinal grafts evoke immune privilege when placed into the anterior chamber of the eye? 2.What is the fate of intraocular retinal transplants placed in eye of normal mice? of previously immunized mice? of mice with deviant immunity to antigens on the graft? 3.Are the vitreous cavity, subretinal space, and other elements of the posterior compartment of the eye immunologically privileged sites for histoincompatible retinal transplants? Our experimental approaches will include clinical, histopathological, and immunological evaluations. We expect to reveal the extent of immune privilege in the eye for intraocular retinal transplants, as a prelude to the long-term goal of using such transplants to restore sight in eyes blinded by degenerative retinal diseases. Of perhaps equal importance, we anticipate that the novel nature of the experiments may permit us to discover previously unsuspected cellular and molecular interactions between the immune system and the tissues of the eye and nervous system.